There are known developing devices used in electrophotographic image forming apparatuses having an image carrying member on which is formed an electrostatic latent image, a developing agent carrying member which supplies a developing agent to the image carrying member, and a seal member which is in tight contact with the developing agent carrying member. The developing agent carrying member is generally columnar in shape. The seal member is disposed between the housing of the developing device and a shaft end portion of the developing agent carrying member, and slides over the outer perimeter face of the developing agent carrying member during developing operations. External leakage of developing agent from the shaft end portion of the developing agent carrying member is prevented by the seal member.
There is known such a developing device which has a developing roller as the developing agent carrying member, with a groove formed on the surface of the seal member serving as the face of contact as to the developing roller. The groove on the seal member is configured so as to cause toner to move to the middle portion of the developing roller in the axial line direction, due to rotations of the developing roller. Accordingly, even if toner works its way into between the developing roller and seal member during developing operations, the toner is guided to the middle side of the developing roller in the axial line direction by the groove in the seal member, due to rotations of the developing roller, and is returned into the housing.